1. Field of the Invention
The present invention relates to an ultrasonic inspection device and an ultrasonic inspection method visualizing a state of defect, void, and peeling of a joint portion and the like in a structure and a component, using ultrasonic waves transmitted/received by an ultrasonic transducer composed of a plurality of piezoelectric transducing parts which are arranged in a matrix or in a line and independently formed.
2. Description of the Related Art
In a conventional ultrasonic inspection device using an ultrasonic transducer composed of a plurality of piezoelectric transducing parts which are arranged in a matrix or in a line and independently formed, when the ultrasonic inspection device needs to automatically inspect an inspection object for flaws within a certain range, it is typical to provide a scanner mechanism which drives the ultrasonic transducer above the inspection object surface to scan the inspection object.
The scanner mechanism is composed using an orthogonal robot including axes such as an X-axis, a Y-axis, and a Z-axis, or an A-axis (a rotation axis around the X-axis), a B-axis (the rotation axis around the Y-axis), and a C-axis (the rotation axis around the Z-axis) as necessary, or an industrial robot mainly composed of an arm mechanism or the like.
The path of driving the ultrasonic transducer by the scanner mechanism needs to be created in advance based on the shape of the inspection object taking the aperture width of the ultrasonic transducer as one scan width. Methods of the creation include a method of creating the path in advance using computer software based on shape design data of the inspection object, and a method of actually driving the scanner mechanism and teaching and registering path information point by point. Further, a method of obtaining the actual shape of the inspection object by distance measurement by a distance sensor is also known (see, for example, JP-A 63-309852 (KOKAI)).
In an ultrasonic inspection, it is necessary that the ultrasonic wave emitted from the ultrasonic transducer enters the inspection object in a manner to be orthogonal to the surface thereof. Further, an ultrasonic inspection device performing flaw detection by the aperture synthesis method is also known (see, for example, JP-A 2004-53360 (KOKAI)), and it is important to keep the distance between the ultrasonic transducer and the inspection object surface constant in such an ultrasonic inspection device in which the flaw detection is performed by the aperture synthesis method. Note that there is a known technique which reduces mutual interference of ultrasonic waves using a plurality of ultrasonic probes having different frequencies to be able to inspect states of a plurality of joint portions at the same time see, for example, JP-A 11-295276 (KOKAI)).
Among the above-described conventional techniques, in the method of creating the path of driving the ultrasonic transducer in advance using the computer software based on shape design data, it is relatively easily possible to create the path information. However, the path information is based on the ideal shape design data, and therefore inconsistency may occur between the data and the actual shape of the inspection object, due to the working accuracy. Further, the inspect ion object is subjected to inspection while being fixed in the scanner mechanism, in which it is not easy to fix an inspection object in a complicated shape with high accuracy and high reproducibility.
Further, in the method of actually driving the scanner mechanism and teaching and registering path information point by point, a lot of time is required to teach and register path information point by point. Especially for a scanner mechanism having a complicated axis configuration, very complicated procedure and operation are necessary to teach and register path information, and therefore teaching and registering exact path information is a work accompanied by great difficulties. Further, even after obtaining shape data, there occurs inconsistency in path information unless the inspection object is accurately set in the scanner mechanism.
Further, also in the method of obtaining the actual shape by distance measurement by a distance sensor, unless the inspection object is accurately set in the scanner mechanism after obtaining the shape data, there occurs inconsistency in path information.
As described above, it has been difficult to create the path information which completely coincides with the state of the real inspection object.
To the above problem, there is a conceivable method that is capable of autonomously adjusting the error factor existing between the path information of the scanner mechanism and the real inspection object through use of a function of sensing the distance and the inclination between the ultrasonic transducer and the inspection object surface, and an actuator function of controlling the ultrasonic transducer.
Here, it is necessary to interpose a medium such as water or the like between the ultrasonic transducer and the inspection object in order for an ultrasonic wave to enter from the ultrasonic transducer to the inspection object or for the ultrasonic transducer to receive an ultrasonic echo from the inspection object. Under such circumstances, the ultrasonic inspection is often performed while the ultrasonic transducer and the inspection object are sunk in water. For the ultrasonic inspection in water, use of an ultrasonic probe as a sensor for detecting the distance or the inclination is conceivable as one method for integrating the function of sensing the distance or the inclination between the ultrasonic transducer and the inspection object surface, into the ultrasonic transducer. The ultrasonic probe that is usable in water and has an appropriate size condition and so on is selectable.
However, in the case where the ultrasonic probe is used as the sensor for detecting the distance or the inclination, interference of ultrasonic waves may occur between the detecting ultrasonic transducer and the ultrasonic probe for detecting the distance or the inclination because the ultrasonic probe uses the same ultrasonic wave as that of the ultrasonic transducer used for ultrasonic inspection. Occurrence of the interference of ultrasonic waves will deteriorate the inspection data and inspection image obtained via the ultrasonic transducer, or disable correct measurement of the distance and the inclination between the inspection object measured by the ultrasonic probe and the ultrasonic transducer.
Further, in the case where a plurality of ultrasonic probes are used for detecting the distance or the inclination, interference of ultrasonic waves may occur between the plural ultrasonic probes. Occurrence of such interference of ultrasonic waves will disable correct measurement of the distance and the inclination between the inspection object measured by the ultrasonic probes and the ultrasonic transducer.
The present invention has been made in consideration of the above-described circumstances in the prior art, and an object thereof is to provide an ultrasonic inspection device and an ultrasonic inspection method each capable of measuring the distance and the inclination between an ultrasonic transducer and an inspection object surface with high accuracy, and obtaining high-quality inspection data and inspection image.